1. Field of the Invention
This invention relates to a valve stem having a tubular upper portion and a cylindrical lower portion having a beveled upper surface terminating at the base of the tubular upper portion to form an annular groove therebetween such that the side wall of the upper portion and the beveled surface of the lower portion form two separate sealing surfaces.
2. Description of the Prior Art
Valve assemblies for aerosol dispensers generally comprise a hollow valve body having a spring biased valve stem disposed therein.
Commonly, these valve stems comprise a hollow tubular body closed at the lower extreme and including a dispensing port formed in the side wall thereof. Normally the valve stem is biased in the closed position where the dispensing port abuts a gasket type sealing ring disposed in the mounting cup turret to prevent product or propellant from flowing therethrough.
Another common valve stem configuration comprises a solid inverted mushroom shaped member wherein the sealing means is disposed between the mushroom head and the lower surface on the valve body. Thus, as the stem is depressed into the valve body, the seal between the mushroom head and the body is broken releasing the contents from within the dispenser.
Generally, the efficiency and efficacy of these seals has been satisfactory for most liquid products. However, with the increasing use of solid products such as powder and the like, these seals have been found to be less effective. The solid particles tend to become lodged between the sealing surfaces thereby reducing the seal therebetween thus permitting the propellant and/or product to escape when the dispenser is not actuated. Obviously, this is unacceptable from a consumer standpoint.
Thus, it is apparent that a need exists for an effective seal that is within reasonable cost and production parameters.